The movie was originally to be titled
Mrs. Frisby and the Rats of NIMH, but in 1981 (a year before its release) Don Bluth was approached by lawyers representing the Wham-O toy company, who threatened a lawsuit to protect their "Frisbee" trademark.
Thus, in short-order, the film was re-titled
The Secret of NIMH, and the main character's name was changed from "Frisby" to "Brisby".
This meant that all the dialogue referring to Mrs. Brisby by name had to be re-recorded .. but in the case of John Carradine (the voice of the Great Owl), he had become too ill at that point to come in to the studio .. so his lines were 'fixed' with some clever audio editing: splicing in a hard "B" from elsewhere in his dialogue!
Actually, a single instance of the "Frisby" name went overlooked: in the scene where Mrs. Brisby is trying to find an entrance to the rosebush, and Jeremy wants to be of help, she says (out of desperation), "If you
really wanted to help me -- you'd
go away!" To which Jeremy replies, "Well, that's very brave of you, Mrs. Friz, but I can't let you do that."
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I read the book
Mrs. Frisby and the Rats of NIMH in 1978 (when I was 8 years old), and absolutely loved it; even at the time, I thought it would make a great animated film. So I was overjoyed, a mere five years later, to see
The Secret of NIMH. And I loved it, too!
While there are major differences between the book and the film, the 'heart-and-soul' of the story -- Mrs. Frisby's desperate plight, and her steadfast determination to save her family -- remains essentially unchanged.
The magic and mysticism Bluth 'injected' into the Rats' world gives the film a 'personality' apart from the book .. it definitely gives the Rats a more 'cinematic' presence. The fact that the 'magic' is never fully explained is actually what made me love the film -- it made the Rats that much
more mysterious; as much an enigma to the viewer, as they were to the simple field mouse whose eyes we see them through.
